If you like anime this game is definitely for you! Some of the cut-scenes in the first game are done in that style and all of the cut-scenes in the expansion are. On top of that the story and voices scream anime.
As far as gameplay goes it was alright. The attacks are rather limited and your opponents only get more and more difficult leaving you feeling inadequate. It certainly feels like an old-school RPG in the sense that not a lot changes. You will find yourself stuck in the same situations, with the same attacks over and over again. If you get bored with relativity easily than don't play this game.
Lastly, this is certainly a Kojima game. The art style is reminiscent of the Tanker Incident in MGS2. Also, they will give you random puzzles to solve that are key to the story with little to no clues as how to solve them.
This game is certainly for old school, patient gamers and/or Kojima fans. I suggest that you at least give this game a chance - even with it's flaws it's surprisingly entertaining for a Mecha style game.
The Original Zone of the Enders is the only reason why this game did not receive a higher score. Repetitive game play, corny dialogue, horrible voice acting, and a surprisingly short single player campaign that maybe last 4-5 hours.
2nd Walker is where the real fun begins. Konami improved on many of the original ZOE short comings. The biggest improvement is the fact that you don't need to return to a previous area 3 times to collect passcodes. Combat is smoother, and more challenging forcing the user to use every aspect of controlling the OF. Voice acting is decent, animation is improved. New pilot that finally replaces the cry baby leo from the first one.
Either way its a great rental, I highly recommend.